Oxidation of Pt(111) under near-ambient conditions

Phys Rev Lett. 2011 Nov 4;107(19):195502. doi: 10.1103/PhysRevLett.107.195502. Epub 2011 Nov 4.


The oxidation of Pt(111) at near-ambient O2 pressures has been followed in situ using x-ray photoelectron spectroscopy (XPS) and ex situ using x-ray absorption spectroscopy (XAS). Polarization-dependent XAS signatures at the O K edge reveal significant temperature- and pressure-dependent changes of the Pt-O interaction. Oxide growth commences via a PtO-like surface oxide that coexists with chemisorbed oxygen, while an ultrathin α-PtO2 trilayer is identified as the precursor to bulk oxidation. These results have important implications for understanding the chemical state of Pt in catalysis.